1. Technical Field
The present invention relates to optical systems, and particularly to an optical system having lenses with adjustable focal length associated therewith.
2. Discussion of Related Art
Variable focus lenses are widely used in optical systems. Optical systems incorporating such lenses can, for example, provide focused images of objects at varying distances from the lens on an image plane without changing the distance between the lens and the image plane. The variable focus lenses can also be used in optical systems that provide varying magnification without changing lenses.
Many types of variable focus lenses have been devised. The design most widely used at present in optical instruments, such as cameras, telescopes, binoculars and microscopes, is a multi-element lens module wherein the focal length is varied by changing the internal spacing of one or more of the elements along the optical axis. Generally, the lens system usually uses an actuator, such as step motor, to drive the lens module. However, the step motor is relatively large in volume and consumes a substantial amount of power, especially relative to the amount of power that can be stored in the typical battery system. Use of the motor needs more space for movements of the lenses, which makes the lens system awkward and bulky
Therefore, what is needed is an optical system adapted for variable focusing without the need for large mechanical movement.